Anti-glare surface treatment method and articles thereof

ABSTRACT

A glass article including: at least one anti-glare surface having haze, distinctness-of-image, surface roughness, and uniformity properties, as defined herein. A method of making the glass article includes, for example: depositing deformable particles on at least a portion of a glass surface of the article; causing the deposited deformable particles on the surface to deform and adhere to the surface; and contacting the surface having the adhered particles with an etchant to form the anti-glare surface. A display system that incorporates the glass article, as defined herein, is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of and claims priority from and thebenefit of U.S. application Ser. No. 13/270,345, filed on Oct. 11,2011—now U.S. Pat. No. 9,017,566, issued on Apr. 28, 2015, which claimsthe benefit of U.S. Provisional Application Ser. No. 61/417,674, filedon Nov. 29, 2010, and entitled “anti-glare surface treatment method andarticles thereof,” the content of which is relied upon and incorporatedherein by reference in its entirety.

CROSS-REFERENCE TO RELATED COPENDING APPLICATION(S)

This application is related to commonly owned and assigned U.S. Ser. No.61/329,936, filed Apr. 30, 2010, entitled “Anti-Glare Surface TreatmentMethod and Articles Thereof,” and U.S. Ser. No. 61/372,655 filed Aug.11, 2010, entitled “Anti-Glare Surface Treatment Method and ArticlesThereof.”

BACKGROUND

The disclosure relates generally to methods of making and using ananti-glare surface and articles thereof.

SUMMARY

The disclosure provides a method of making an anti-glare surface,articles made by the method, and a display system incorporating thearticle having the anti-glare surface. In embodiments, the method ofmaking includes depositing sacrificial deformable particles on at leastone surface of an article, treating the deformable particle populatedsurface, i.e., particulated surface, to at least adhere the particles tothe surface, and contacting the resulting adhered particulated surfacewith an etchant to form the anti-glare roughened surface.

BRIEF DESCRIPTION OF THE DRAWING(S)

In embodiments of the disclosure:

FIG. 1 shows a schematic of the method of making an anti-glare layer ona glass surface.

FIG. 2 shows an example microscopic image of wax particles that wereslot-die coated on a Gorilla® Glass surface.

FIG. 3 shows an example microscopic image of the Gorilla® Glass surfaceof FIG. 2 that was subsequently thermally treated at 75° C. for 30seconds.

FIGS. 4A and 4B respectively show a microscopic image at two differentmagnifications of an example etched surface after the glass sample wasslot-die coated with a polymer particle formulation and then thermallytreated at 106° C. for 30 seconds.

FIGS. 5A and 5B show, respectively, surface analysis images at high(FIG. 5A) and low (FIG. 5B) magnifications for surface roughness of anetched coupon after coating and thermal treatment at 106° C. for 30seconds and then 30 seconds etch time.

FIGS. 6A and 6B show, respectively, exemplary microscopic images ofparticles that were slot-die coated on a Gorilla® Glass surface, beforeand after they were thermally treated at 80° C. for 40 seconds.

FIGS. 7A and 7B show, respectively, exemplary microscopic images ofparticles that were slot-die coated on a Gorilla® Glass surface, beforeand after they were thermally treated at 105° C. for 30 seconds.

FIGS. 8A and 8B show histograms representing examples of the particlesize distribution for exemplary particle suspension formulationsmeasured by laser light scattering.

DETAILED DESCRIPTION

Various embodiments of the disclosure will be described in detail withreference to drawings, if any. Reference to various embodiments does notlimit the scope of the invention, which is limited only by the scope ofthe claims attached hereto. Additionally, any examples set forth in thisspecification are not limiting and merely set forth some of the manypossible embodiments of the claimed invention.

In embodiments, the disclosed articles, and the disclosed method ofmaking and use provide one or more advantageous features or aspects,including for example as discussed below. Features or aspects recited inany of the claims are generally applicable to all facets of theinvention. Any recited single or multiple feature or aspect in any oneclaim can be combined or permuted with any other recited feature oraspect in any other claim or claims.

Definitions

“Anti-glare” or like terms refer to a physical transformation of lightcontacting the treated surface of an article, such as a display, of thedisclosure that changes, or to the property of changing light reflectedfrom the surface of an article, into a diffuse reflection rather than aspecular reflection. In embodiments, the surface treatment can beproduced by mechanical, chemical, electrical, and like etching methods,or combinations thereof. Anti-glare does not reduce the amount of lightreflected from the surface, but only changes the characteristics of thereflected light. An image reflected by an anti-glare surface has nosharp boundaries. In contrast to an anti-glare surface, ananti-reflective surface is typically a thin-film coating that reducesthe reflection of light from a surface via the use of refractive-indexvariation and, in some instances, destructive interference techniques.

“Contacting” or like terms refer to a close physical touching that canresult in a physical change, a chemical change, or both, to at least onetouched entity. In the present disclosure various particulate depositionor contacting techniques, such as spray coating, dip coating, slotcoating, and like techniques, can provide a particulated surface whencontacted as illustrated and demonstrated herein. Additionally oralternatively, various chemical treatments of the particulated surface,such as spray, immersion, dipping, and like techniques, or combinationsthereof, as illustrated and demonstrated herein, can provide an etchedsurface when contacted with one or more etchant compositions.

“Distinctness-of-reflected image,” “distinctness-of-image,” “DOI” orlike term is defined by method A of ASTM procedure D5767 (ASTM 5767),entitled “Standard Test Methods for Instrumental Measurements ofDistinctness-of-Image Gloss of Coating Surfaces.” In accordance withmethod A of ASTM 5767, glass reflectance factor measurements are made onthe at least one roughened surface of the glass article at the specularviewing angle and at an angle slightly off the specular viewing angle.The values obtained from these measurements are combined to provide aDOI value. In particular, DOI is calculated according to equation (1):

$\begin{matrix}{{DOI} = {\left\lbrack {1 - \frac{Ros}{Rs}} \right\rbrack \times 100}} & (1)\end{matrix}$where Rs is the relative amplitude of reflectance in the speculardirection and Ros is the relative amplitude of reflectance in anoff-specular direction. As described herein, Ros, unless otherwisespecified, is calculated by averaging the reflectance over an angularrange from 0.2° to 0.4° away from the specular direction. Rs can becalculated by averaging the reflectance over an angular range of ±0.05°centered on the specular direction. Both Rs and Ros were measured usinga goniophotometer (Novo-gloss IQ, Rhopoint Instruments) that iscalibrated to a certified black glass standard, as specified in ASTMprocedures D523 and D5767. The Novo-gloss instrument uses a detectorarray in which the specular angle is centered about the highest value inthe detector array. DOI was also evaluated using 1-side (black absorbercoupled to rear of glass) and 2-side (reflections allowed from bothglass surfaces, nothing coupled to glass) methods. The 1-sidemeasurement allows the gloss, reflectance, and DOI to be determined fora single surface (e.g., a single roughened surface) of the glassarticle, whereas the 2-side measurement enables gloss, reflectance, andDOI to be determined for the glass article as a whole. The Ros/Rs ratiocan be calculated from the average values obtained for Rs and Ros asdescribed above. “20° DOI,” or “DOI 20°” refers to DOI measurements inwhich the light is incident on the sample at 20° off the normal to theglass surface, as described in ASTM D5767. The measurement of either DOIor common gloss using the 2-side method can best be performed in a darkroom or enclosure so that the measured value of these properties is zerowhen the sample is absent.

For anti-glare surfaces, it is generally desirable that DOI berelatively low and the reflectance ratio (Ros/Rs) of eq. (1) berelatively high. This results in visual perception of a blurred orindistinct reflected image. In embodiments, the at least one roughenedsurface of the glass article has a Ros/Rs greater than about 0.1,greater than about 0.4, and, greater than about 0.8, when measured at anangle of 20° from the specular direction using the 1-side methodmeasurement. Using the 2-side method, the Ros/Rs of the glass article ata 20° angle from the specular direction is greater than about 0.05. Inembodiments, the Ros/Rs measured by the 2-side method for the glassarticle is greater than about 0.2, and greater than about 0.4. Commongloss, as measured by ASTM D523, is insufficient to distinguish surfaceswith a strong specular reflection component (distinct reflected image)from those with a weak specular component (blurred reflected image).This can be attributable to the small-angle scattering effects that arenot measurable using common gloss meters designed according to ASTMD523.

“Transmission haze,” “haze,” or like terms refer to a particular surfacelight scatter characteristic related to surface roughness. Hazemeasurement is specified in greater detail below.

“Roughness,” “surface roughness (Ra),” or like terms refer to, on amicroscopic level or below, an uneven or irregular surface condition,such as an average root mean squared (RMS) roughness or RMS roughnessdescribed below.

“Gloss,” “gloss level,” or like terms refer to, for example, surfaceluster, brightness, or shine, and more particularly to the measurementof specular reflectance calibrated to a standard (such as, for example,a certified black glass standard) in accordance with ASTM procedureD523, the contents of which are incorporated herein by reference intheir entirety. Common gloss measurements are typically performed atincident light angles of 20°, 60°, and 85°, with the most commonly usedgloss measurement being performed at 60°. Due to the wide acceptanceangle of this measurement, however, common gloss often cannotdistinguish between surfaces having high and lowdistinctness-of-reflected-image (DOI) values. The anti-glare surface ofthe glass article has a gloss (i.e.; the amount of light that isspecularly reflected from sample relative to a standard at a specificangle) of up to 90 SGU (standard gloss units), as measured according toASTM standard D523, and, in one embodiment, has a gloss in a range fromabout 60 SGU up to about 80 SGU. See also the DOI definition above.

“Adhere,” “adhering,” “anneal,” “annealing,” or like terms individuallyor collectively refer to the state or action of the deposited particleswhen caused to deform and subsequently further hold fast, bind to, stickto, and like associative descriptors, to the glass surface beingtreated, including particle-surface attraction or association(adhesion), particle-particle attraction or association (cohesion), andlike interactions.

“Deform,” “deformable,” “deforming,” or like terms refer to the state oract of the deposited particles when caused to adhere to the glasssurface by, for example, thermal, mechanical, radiation, or like means.

“ALF” or “average characteristic largest feature size” or like termsrefer to a measure of surface feature variation in the x- andy-directions, i.e., in the plane of the substrate, as discussed furtherbelow.

“Sparkle,” “display sparkle,” or like terms refer to the relationshipbetween the size of features on the at least one roughened glass surfaceand pixel pitch, particularly the smallest pixel pitch, is of interest.Display “sparkle” is commonly evaluated by human visual inspection of amaterial that is placed adjacent to a pixelated display. ALF and itsrelationship to display “sparkle” has been found to be a valid metricfor different materials having different surface morphologies, includingglasses of varying composition and particle-coated polymer materials. Astrong correlation between average largest characteristic feature size(ALF) and visual ranking of display sparkle severity exists acrossmultiple different sample materials and surface morphologies. Inembodiments, the glass article can be a glass panel that forms a portionof a display system. The display system can include a pixelated imagedisplay panel that is disposed adjacent to the glass panel. The smallestpixel pitch of the display panel can be greater than ALF.

“Uniformity,” “uniform” or like terms refer to the surface quality of anetched sample. Surface uniformity is commonly evaluated by human visualinspection at various angles. For example, the glass article sample isheld at about eye level, and then slowly turned from 0 to 90 deg., undera standard, white fluorescent light condition. When no pin-holes,cracks, waviness, roughness, or other like defects can be detected bythe observer, the surface quality is deemed “uniform”; otherwise, thesample is deemed not uniform. “Good” or “OK” ratings mean that theuniformity is acceptable or satisfactory with the former beingsubjectively better than the latter.

“Include,” “includes,” or like terms means encompassing but not limitedto, that is, inclusive and not exclusive.

“About” modifying, for example, the quantity of an ingredient in acomposition, concentrations, volumes, process temperature, process time,yields, flow rates, pressures, and like values, and ranges thereof,employed in describing the embodiments of the disclosure, refers tovariation in the numerical quantity that can occur, for example: throughtypical measuring and handling procedures used for preparing materials,compositions, composites, concentrates, or use formulations; throughinadvertent error in these procedures; through differences in themanufacture, source, or purity of starting materials or ingredients usedto carry out the methods; and like considerations. The term “about” alsoencompasses amounts that differ due to aging of a composition orformulation with a particular initial concentration or mixture, andamounts that differ due to mixing or processing a composition orformulation with a particular initial concentration or mixture. Theclaims appended hereto include equivalents of these “about” quantities.

“Consisting essentially of” in embodiments can refer to, for example:

a method of making a glass article by depositing particles on a surfaceof the article; adhering the particles to a surface of the article; andcontacting the particulated surface with an etchant, as defined herein;or

a glass article having an anti-glare surface having haze,distinctness-of-image, surface roughness, and uniformity properties, asdefined herein; or

a display system that incorporates the glass article, as defined herein.

The method of making, the article, the display system, compositions,formulations, or any apparatus of the disclosure, can include thecomponents or steps listed in the claim, plus other components or stepsthat do not materially affect the basic and novel properties of thecompositions, articles, apparatus, or methods of making and use of thedisclosure, such as particular reactants, particular additives oringredients, a particular agent, a particular surface modifier orcondition, or like structure, material, or process variable selected.Items that may materially affect the basic properties of the componentsor steps of the disclosure or that may impart undesirablecharacteristics to the present disclosure include, for example, asurface having objectionable high glare or high gloss properties, forexample, having a haze, a distinctness-of-image, a surface roughness, auniformity, or a combination thereof, that are beyond the values,including intermediate values and ranges, defined and specified herein.

The indefinite article “a” or “an” and its corresponding definitearticle “the” as used herein means at least one, or one or more, unlessspecified otherwise.

Abbreviations, which are well known to one of ordinary skill in the art,may be used (e.g., “h” or “hr” for hour or hours, “g” or “gm” forgram(s), “mL” for milliliters, and “rt” for room temperature, “nm” fornanometers, and like abbreviations).

Specific and preferred values disclosed for components, ingredients,additives, and like aspects, and ranges thereof, are for illustrationonly; they do not exclude other defined values or other values withindefined ranges. The compositions, apparatus, and methods of thedisclosure can include any value or any combination of the values,specific values, more specific values, and preferred values describedherein.

Chemically strengthened glasses are used in many handheld andtouch-sensitive devices as display windows and cover plates whereresistance to mechanical damage can be significant to the visualappearance and functionality of the product. During chemicalstrengthening, larger alkali ions in a molten salt bath are exchangedfor smaller mobile alkali ions located within a certain distance fromthe glass surface. The ion-exchange process places the surface of theglass in compression, allowing it to become more resistant to anymechanical damage it is commonly subjected to during use.

Reduction in the specular reflection, a significant factor in glare,from many display surfaces is often desired, especially by manufacturerswhose products are designed for outdoor use where glare can beexacerbated by sunlight. One way to reduce the intensity of the specularreflection, quantified as gloss, is to roughen the glass surface orcover it with a textured film. The dimensions of the roughness ortexture should be large enough to scatter visible light, producing aslightly hazy or matte surface, but not too large as to significantlyaffect the transparency of the glass. Textured or particle-containingpolymer films can be used when maintaining the properties (e.g., scratchresistance) of the glass substrate are not important. While these filmsmaybe cheap and easy to apply, they are subject to easy abrasion whichcan reduce the display functionality of the device. Another shortfall ofusing films or coatings is that they can interfere with the operationof, or diminish the performance of certain touch-sensitive devices.Another approach to roughening the glass surface is chemical etching.U.S. Pat. Nos. 4,921,626, 6,807,824, 5,989,450, and WO2002053508,mention glass etching compositions and methods of etching glass with thecompositions. Wet etching is a method of generating an anti-glaresurface on the glass while preserving its inherent mechanical surfaceproperties. During this process, the glass surface is exposed tochemicals which degrade the surface to the correct roughness dimensionsfor the scattering of visible light. When micro-structural regionshaving differential solubility are present, such as in soda limesilicate glasses, a roughened surface can be formed by placing the glassin a (typically fluoride-ion containing) mineral acid solution. Suchselective leaching or etching is generally ineffective at generating auniform, anti-glare surface on other display glasses lacking suchdifferentially soluble micro-structural regions, such as alkaline earthaluminosilicates and mixed alkali borosilicates, and for alkali andmixed alkali aluminosilicates containing, for example, lithium, sodium,potassium, and like compositions, or combinations thereof.

One result of roughening a glass surface is to create “sparkle,” whichis perceived as a grainy appearance. Sparkle is manifested by theappearance of bright and dark or colored spots at approximately thepixel-level size scale. The presence of sparkle reduces the viewabilityof pixilated displays, particularly under high ambient lightingconditions.

In embodiments, the disclosure provides a method of making an articlehaving an anti-glare surface, comprising:

depositing deformable particles on at least one surface of the article;

causing the deposited deformable particles on the surface to deform andadhere to the surface; and

contacting the surface having the deformed and adhered particles with anetchant to form the anti-glare surface.

In embodiments, the disclosure provides a method of making an articlehaving an anti-glare surface, comprising:

depositing particles on at least one surface of an article;

deforming the deposited particles on the surface to adhere to thesurface; and

contacting the surface having the adhered particles with an etchant toform the anti-glare surface.

In embodiments, the disclosure provides a method of making an articlehaving an anti-glare surface, comprising:

depositing particles on a portion of at least one glass surface of thearticle;

heating the particle surface to adhere the deposited particles to theglass surface; and

contacting the glass surface having the adhered particles with anetchant to form the anti-glare surface.

In embodiments, the disclosure provides a method of making an articlehaving an anti-glare surface, comprising:

depositing deformable particles on a portion of at least one glasssurface of the article;

deforming the deposited deformable particles on the surface to adherethe particles to the glass surface; and

contacting the glass surface having the adhered particles with anetchant to form the anti-glare surface.

In embodiments, the disclosure provides a method of making an articlehaving an anti-glare surface, comprising:

depositing polymer particles on a portion of at least one glass surfaceof the article;

heating the polymer particle surface to adhere the deposited polymerparticles to the glass surface; and

contacting the glass surface having the adhered particles with anetchant to form the anti-glare surface.

In embodiments, the glass surface can be, for example, at least one of asoda lime silicate glass, an alkaline earth aluminosilicate glass, analkali aluminosilicate glass, an alkali borosilicate glass, aboroaluminosilicate glass, or a combination thereof, the deformableparticles can be, for example, at least one polymer, wax, or acombination thereof, and the etchant comprises at least one acidselected from HF, H₂SO₄, or a combination thereof. The polymer particlescan include, for example, at least one of a polymer, a copolymer,polymeric nano-particles, cross-linked polymer particles, UV curedpolymer particles, core-shell particles having a core polymer having aT_(g) lower than the shell polymer T_(g), a wax, or a combinationthereof.

In embodiments, the deforming the deposited deformable particles can beaccomplished, for example, by heating. The heating can be accomplishedby any suitable means, such as thermal means, radiation means, pressuremeans, and like methods, or a combination thereof. Such heating meanscan include, for example, a heat gun, a hot gas knife, a convectionoven, a heat lamp, a radiant heater, a press plate, a heated iron, andlike means or a combination thereof.

In embodiments, the depositing deformable particles on at least aportion of at least one glass surface of the article can beaccomplished, for example, by contacting the at least one glass surfacewith a suspension of wax particles, polymer particles, or a combinationthereof. The contacting the at least one glass surface with a suspensionof wax particles, polymer particles, or a combination thereof can beaccomplished with, for example, a slot coater. In embodiments, thedepositing can be accomplished, for example, free of a binder; arheology modifier; or a combination thereof.

In embodiments, the deposited deformable particles can be, for example,a monolayer of particles, an ordered monolayer of particles, a bilayerof particles, an ordered bilayer of particles, and combinations thereof.

In embodiments, the contacting with an etchant can be accomplished by,for example, exposing the glass surface having the deposited deformableparticles to the etchant for about 1 second to about 30 minutes.

In embodiments, the deposited particles can have a D₅₀ diameter of, forexample, from about 1 to about 30 micrometers, including intermediatevalues and ranges.

In embodiments, the deposited particles can by polymer particlescomprising, for example, a thermoplastic, a wax, or a combinationthereof. In embodiments, the deposited particles have a glass transitiontemperature (T_(g)), for example, of from about 25 to about 95° C.,about 25 to about 85° C., about 30 to about 80° C., about 35 to about50° C., and like glass transition temperatures, including intermediatevalues and ranges.

In embodiments, depositing polymer particles, wax particles, or amixture of polymer particles and wax particles on the surface of thearticle can be accomplished with a slot-die coater, and like coatingapparatus and methods.

In embodiments, the deposited particles on the surface can be, forexample, a mono-layer to a multi-layer having a wet thickness of, forexample, from about 1 to about 200 micrometers, such as from about 2 toabout 100 micrometers including intermediate values and ranges, and adry thickness of, for example, from about 0.1 to about 50 micrometers,such as from about 1 to about 25 micrometers including intermediatevalues and ranges.

In embodiments, the method can further comprise treating the resultingroughened surface with a low-surface energy coating, for example, afluorinated compound, to reduce wetting and permit easy clean-up.

In embodiments, the method can further comprise, after etching, washingthe resulting anti-glare surface, chemically strengthening theanti-glare surface, or a combination thereof.

In embodiments, the method can further comprise, prior to etching,contacting at least another surface of the article with an optionallyremovable, etch-resistant protective layer.

In embodiments, the disclosure provides a glass article prepared by anyof the aforementioned processes including combinations or permutationsthereof.

In embodiments, the disclosure provides a glass article comprising:

at least one anti-glare surface having:

-   -   a haze of from about 0.1 to about 30;    -   a distinctness-of-image (DOI 20°) of from about 25 to about 85;    -   a surface roughness (Ra) of from about 50 to about 500 nm; and    -   an average roughness peak-to-valley difference profile of from        about 0.1 to about 10 micrometers.

In embodiments, the glass article can have anti-glare surface having,for example, a distribution of topographic features having, for example,an average diameter of about 1 to about 100 micrometers. A preferreddiameter for topographic features can be, for example, from about 0.1 toabout 20 micrometers, including intermediate values and ranges.

In embodiments, the glass article can be, for example, a sheet ofprotective cover glass of a display device.

In embodiments, the disclosure provides a display system comprising, forexample:

a glass panel having at least one roughened anti-glare surface preparedby any of the above mentioned methods having:

-   -   a haze of less than about 30;    -   a distinctness-of-image (DOI 20°) of about 25 to about 85;    -   a surface roughness (Ra) of about 50 to about 500 nm; and    -   an average roughness peak-to-valley difference profile of about        0.1 to about 10 micrometers; and

a pixelated image-display panel adjacent to the glass panel.

In embodiments, a preferred haze can be, for example, less than about10, an even more preferred haze can be, for example, about 6 to about 9,and an even more preferred haze can be, for example, about 5 to about 6or below, including intermediate values and ranges.

In embodiments, the disclosure provides a coating and a wet etchingprocess to form a nano- to micro-scale textured surface on a glasssurface, such as silicate glasses. In embodiments, the process involvescoating, for example, low molecular weight polymer particles, waxparticles, or combinations thereof, on the glass surface, followed by athermal treatment at a relatively low temperature, for example, fromabout 30 to about 140° C., from about 35 to about 135° C., from about 40to about 130° C., from about 45 to about 100° C., from about 50 to about90° C., from about 55 to about 85° C., from about 60 to about 80° C.,and like temperatures, including intermediate values and ranges, and fora sufficient time to promote deformation and adhesion of the particlesonto the glass surface. The particulated surface is then etched, forexample, in an HF, or multi-component acid solution. The etch solutioncreates preferential etching around deformed particles on the glasssurface to form an AG roughened surface layer on the processed glassarticle.

A known etching process to produce an anti-glare layer on a glasssurface can involve at least three baths. For example, the first bathcan contain ammonium biflouride (ABF), for growing ABF crystals on theglass surface. The second bath can contain H₂SO₄ acid to remove thecrystals. The third bath can be a mixture of H₂SO₄/HF to smooth theglass surface. Typical processing times, from start to finish for thethree-bath process, can be for example, of about 60 about 80 minutes.

Corning, Inc., has developed an alternative process, as disclosed incommonly owned and assigned U.S. Ser. No. 61/329,936, which involves theuse of a particle suspension. The particle suspension can be used tocreate a differential etching-mask when applied to the glass surface andfollowed by etching. This process is significantly faster, but is stillmore complex and costly compared to the presently disclosed process. Thedisclosed process can have significant benefits compared to the otherprocesses including, for example, the following features.

The process reproducibly provides anti-glare glass sheets havingsignificantly improved appearance properties including, for example,very low sparkle such as from about 4 to about 6 compared to sparklesuch as about 7 to about 12 attainable from prior processes.

The haze characteristics of the glass article processed in accord withthe disclosure can be adjustable from low to very high values. Low hazecan be desirable for applications requiring high display contrast, whilehigh haze can be useful for optical designs having scattering, such asedge illumination, or for aesthetic reasons such as reducing the “blackhole” appearance of the display in the off state. The general preferencefor low versus high haze (and the acceptance of performance trade-offs)can be motivated by customer or end-user preferences, and their finalapplication and use mode.

The disclosed process permits the surface roughness of one or both sidesof the glass sheet to be adjusted over a spectrum of roughness valuesfrom low to very high values. Low roughness is generally used to createsmall-angle scattering, resulting in low DOI with low haze andcorresponding high display contrast. However, high roughness can bedesirable for some applications, such as in certain touch-sensitivedisplay devices where a rough surface can provide a desirable “glidingfeel” for the user's point-of-contact, such as finger, knuckle, toe, ornose. The effect of high roughness can also be useful in non-displayapplications, such as mouse pad surfaces. For these touch applications,it may also be desirable to post-treat the rough surface with alow-surface energy coating such as a fluorosilane. This can reducesurface friction, improve the “gliding feel” effect, and also make thesurfaces less wettable by oil and water, and easier to clean.

The widely adjustable haze and roughness values could be achieved usingshort etch times, for example, about 30 seconds, and having very littleglass thickness loss, for example, less than about 5 microns, relativeto prior anti-glare processes.

The disclosed process can use lower acid concentrations or shorter etchtimes to achieve high haze and roughness values compared to the processdescribed in the copending commonly owned and assigned U.S. Ser. No.61/372,655 application

The ability to adjust haze, DOI, roughness, or combinations thereof,through the particle annealing temperature provides new flexibility forusing the same acid compositions for multiple haze levels, oralternatively, to reduce the acid concentration used to achieve a givenhaze level. The ability to control the glass surface profile throughparticle deformation prior to etching can be independent of the coatingmethod (wet or dry).

The slot die coating process used to apply particles to the glass allowsa very thin layer, for example, 1 to 2 layers, or in some instances lessthan a monolayer, of particles on the surface. This improves the abilityof the acid to infiltrate the spaces in the mask, resulting moreefficient etching, less acid consumption, and less particle consumption.

In the copending commonly owned and assigned U.S. Ser. No. 61/329,936application, an anti-glare surface was created by suspending particlesin a liquid vehicle with other components such as a rheology modifier, adeformer, a binder, etc., then applied, such as sprayed, onto the glasssurface, followed by drying, and etching. The combination of particlebinders, rheology modifier, and other components in the liquid addcomplexity and could compromise the strength of the acid, for example,weakening the acid by reacting with one or more of the otheringredients. The present disclosure can be accomplished without theseadditives, which can further simplify process complexity and reduceprocess costs.

In embodiments, the disclosure provides a wet etch method for generatingan anti-glare surface on the glass while preserving its inherentmechanical surface properties. During this process, a particulated glasssurface is exposed to chemicals which can degrade the surface to alterthe surface roughness dimensions that are responsible for scatteringvisible light. When significant quantities of mobile alkali ions arepresent in the glass, such as in soda lime silicate glasses, a roughenedsurface can be formed by, for example, contacting the glass surface inan acid etchant solution, such as a solution containing fluoride ion.

In embodiments, the at least one surface of the article can be, forexample, a glass, a composite, a ceramic, a plastic or resin basedmaterial, and like materials, or combinations thereof. In embodiments,the deposited deformable particles can be polymer particles and canadditionally or alternately include, for example, any suitable lowmelting substance: a glass, a composite, a ceramic, a plastic or resinbased material, a metal, a salt, a clay, a polymer, a copolymer,nano-particles, cross-linked polymer particles, UV cured particles, waxparticles, and like materials, or combinations thereof. In embodiments,the etchant can be comprised of at least one acid suitable for etchingthe surface beneath the deposited particles.

In embodiments, the glass surface can be selected from, for example, atleast one aluminosilicate, aluminoborosilicate, soda lime, borosilicate,silica, and like glasses, or a combination thereof, and the etchant cancomprise at least one acid selected from HF, H₂SO₄, or a combinationthereof.

Additionally or alternatively, the contacting the at least one surfacewith particles can be accomplished with a concentrated particlesuspension, or a particle suspension of intermediate concentration. Theparticle-surface contacting can preferably be accomplished using anysuitable method, for example, slot-die coating, screen printing, knifeover roll coating (gap coating), rod coating, spray coating, curtaincoating, and like application methods, or a combination thereof. Thedeposited particles can have, for example, a D₅₀ diameter of from about0.1 to about 30 micrometers, from about 1 to about 30 micrometers, andfrom about 1 to about 25 micrometers, including intermediate values andranges. In embodiments, the particle size range can be, for example,from about 0.1 to about 50 micrometers, 1 to about 30 micrometers, 2 toabout 20 micrometers, and like particle diameters, includingintermediate values and ranges. In embodiments, the particle sizeproperties can be, for example, monomodal, bimodal, tri-modal, and likemodalities, including monodisperse, oligodisperse, polydisperse, andlike particle sizes and particle properties, or combinations thereof.

In embodiments, the contacting of the particulated surface with anetchant can be accomplished by, for example, exposing the surface havingthe deposited particles to the etchant, for example, for from about 1second to about 30 minutes, including intermediate values and ranges,such as about 10 seconds to about 10 minutes, about 20 seconds to about1 minute, and like exposures or intervals

In embodiments, the preparative method can optionally further include,for example, washing the resulting etched anti-glare surface, chemicallystrengthening the anti-glare surface, applying a functional coating orfilm (e.g., a light sensitive or polarizing film) or protective surfacecoating or film, and like coatings or films, or a combination thereof.

In embodiments, when a single-side acid-etch, or like modification isdesired on a sheet of glass, one side of the glass can be protected fromthe etching solution. Protection can be achieved, for example, byapplying an insoluble non-porous coating such as an acrylic wax, or alaminate film having an adhesive layer, for example, an acrylic, asilicone, and like adhesives materials, or combinations thereof. Coatingapplication methods can include, for example, brushing, rolling,spraying, laminating, and like methods. The acid-etch exposed insolublenon-porous protective coating survives the etching process and can bereadily removed after the etching. Removing the protective film from thesurface of the article can be accomplished using any suitable method,such as contacting the protective film with a dissolving liquid, heatingthe film to liquefy and drain, and like methods and materials, or acombination thereof. Thus, the preparative method can optionally furtherinclude, prior to etching, contacting at least another surface, e.g., asecond surface such as the backside of a glass sheet, of the articlewith an optionally removable, etch-resistant protective layer.

In embodiments, the disclosure provides an article prepared by any ofthe preparative processes disclosed herein, such as a glass articleprepared by the above mentioned particle deposition, particledeformation, particle surface adherence, and etching steps. Inembodiments, the preparative processes can be accomplished sequentially,simultaneously, continuously, semi-continuously, batch-wise, and likepermutations, or combinations thereof.

In embodiments, the at least one surface of the article can be a glass,the deposited particles can be a wax, and the etchant can be at leastone acid.

In embodiments, the disclosure provides a glass article comprising:

at least one anti-glare surface having:

-   -   a haze of, for example, from about 0.1 to about 30, such as from        about 0.1 to about 25, from about 0.1 to about 20, from about        0.1 to about 10, and from about 1 to about 10, and low haze,        such as from about 0.1 to about 5, and from about 1 to about 5,        including intermediate values and ranges;    -   a distinctness-of-image (DOI 20°) of, for example, from about 25        to about 85, from about 40 to about 80, from about 45 to about        75, and from about 50 to about 70, including intermediate values        and ranges;    -   a surface roughness (Ra) of, for example, from about 50 to about        500 nm, and from about 80 to about 300 nm, including        intermediate values and ranges; and    -   an average roughness peak-to-valley profile of from about 0.1 to        about 10 micrometers, including intermediate values and ranges.

In embodiments, the glass article having anti-glare surface of thedisclosure can comprise a distribution of topographic features having anaverage diameter of about 0.1 to about 100 micrometers, about 0.1 toabout 50 micrometers, about 0.1 to about 30 micrometers, and likeranges, including intermediate values and ranges.

In embodiments, the disclosure provides a display system including, forexample:

a glass panel having at least one roughened anti-glare surface having:

-   -   a haze of from about 0.1 to less than about 30 including        intermediate values and ranges;    -   a distinctness-of-image (DOI 20°) of from about 40 to about 80,        including intermediate values and ranges;    -   a surface roughness (Ra) of from about 100 to about 300 nm,        including intermediate values and ranges; and    -   an average roughness peak-to-valley difference profile of from        about 0.1 to about 10 micrometers, including intermediate values        and ranges; and

a pixelated image-display panel adjacent to the glass panel.

In embodiments, the disclosure provides a wet etch process to form auniform, nano- to micro-scale textured surface on most silicate glassesand without having a significant impact on chemical strengtheningcapability of the glass. The process includes depositing or otherwisecoating deformable particles, such as polymer, glass, or compositeparticles, on the glass surface, followed by particle deformation orsurface adherence, and acid etching of the particulated surface, such asin an HF, or multi-component acid solution. In embodiments, the HFsolution can preferentially etch around the adhered or annealedparticles on the glass surface, then can optionally, depending uponconditions and duration, subsequently erode the adhered or annealedparticles from the etched surface, and can also reduce the surfaceroughness.

In embodiments, the desired reduced gloss or glare levels can beobtained, for example, by adjusting at least one or more of thefollowing parameters: the viscosity of the particulate suspension, thelevel or concentration of the particles in the suspension, theconcentration of the acid etchant, the amount of particles deposited onthe surface, the particle size distribution (PDS) of the particles used,and the exposure interval or the time that the particle-bearing surfaceof the glass sample is in contact with the acid etchant. In embodiments,the masked surface can be etched, the masked surface can be removed, andthe unmasked etched surface can be etched one or more times, to forexample provide at least some smoothing of the unmasked etched surface.

In embodiments, an anti-glare glass article is provided. The glassarticle can be ion-exchangeable and can have at least one roughenedsurface. The roughened surface has a distinctness-of-reflected image(DOI) of less than 90 when measured at an incidence angle of 20° (DOI at20°). A pixelated display system that includes the anti-glare glassarticle is also provided. The glass article can be, for example, aplanar sheet or panel having two major surfaces joined on the peripheryby at least one edge, although the glass article can be formed intoother shapes such as, for example, a three-dimensional shape. At leastone of the surfaces is a roughened surface including, for example,topological or morphological features, such as, projections,protrusions, depressions, pits, closed or open cell structures,particles, islands, lands, trenches, fissures, crevices, and likegeometries and features, or combinations thereof.

In embodiments, the disclosure provides an aluminosilicate glassarticle. The aluminosilicate glass article can include, for example, atleast 2 mol % Al₂O₃, can be ion-exchangeable, and can have at least oneroughened surface. The aluminosilicate glass article can have at leastone roughened surface comprising a plurality of topographical features.The plurality of topographical features can have an averagecharacteristic largest feature size (ALF) of from about 1 micrometer toabout 50 micrometers.

In embodiments, the disclosure provides a display system. The displaysystem can include, for example, at least one glass panel and apixelated image-display panel adjacent to the glass panel. Theimage-display panel can have a minimum native pixel pitch dimension. Theaverage characteristic largest feature size (ALF) of the glass panel canbe less than the minimum native pixel pitch dimension of the displaypanel. The pixelated image display panel can be, for example, one of anLCD display, an OLED display, or like display devices. The displaysystem can also include touch-sensitive elements or surfaces. The glasscan be, for example, any of the aforementioned glasses, such as analuminosilicate ion-exchanged glass that has at least one roughenedsurface including a plurality of features having an ALF, and theimage-displaying panel has a minimum native pixel pitch. The minimumnative pixel pitch can be, for example, greater than the ALF of theroughened surface of the glass panel.

ALF is measured in the plane of (i.e., parallel to) the roughened glasssurface, and is therefore independent of roughness. ALF is a measurementof feature variation in the x- and y-directions, i.e., in the plane ofthe roughened glass surface. Selecting the largest characteristicfeatures is a useful distinction from other methods that determine amore global average feature size. The largest features are most easilyseen by the human eye and are therefore most important in determiningvisual acceptance of the glass article. In embodiments, the topologicalor morphological features of the at least one roughened surface has anaverage characteristic largest feature (ALF) size of from about 1micrometer to about 50 micrometers, of from about 5 micrometers to about40 micrometers; of from about 10 micrometers to about 30 micrometers;and from about 14 micrometers to about 28 micrometers, includingintermediate values and ranges. The average characteristic largestfeature size is the average cross-sectional linear dimension of thetwenty largest repeating features within a viewing field on a roughenedsurface. A standard calibrated optical light microscope can typically beused to measure feature size. The viewing field is proportional to thefeature size, and typically has an area of approximately30(ALF)×30(ALF). If, for example, the ALF is approximately 10micrometers, then the viewing field from which the twenty largestfeatures are selected is approximately 300 micrometers×300 micrometers.Small changes in the size of the viewing field do not significantlyaffect ALF. The standard deviation of the twenty largest features thatare used to determine ALF should generally be less than about 40% of theaverage value, i.e., major outliers should be ignored since these arenot considered “characteristic” features.

The topography of the anti-glare surface can include, for example,features such as protrusions or projections, depressions, and likefeatures having a maximum dimension of less than about 400 nm. Inembodiments, these topographical features can be separated from eachother or spaced apart at a mean distance of from about 10 nm up to about200 nm. The resulting anti-glare surface can have an average roughness,as measured by the peak-to-valley difference (PV) measure on thesurface. In embodiments, the anti-glare surface can have a RMS roughnessof about 800 nm, of about 500 nm, and about 100 nm.

The features used to calculate ALF are “characteristic;” i.e., at leasttwenty similar features can be located in the proportional viewingfield. Different morphologies or surface structures can be characterizedusing ALF. For example, one surface structure may appear to beclosed-cell repeating structures, another may appear to be small pitsseparated by large plateaus, and a third may appear to be a field ofsmall particles punctuated by intermittent large smooth regions. In eachinstance, the ALF is determined by measuring the twenty largestrepeating surface regions that are substantially optically smooth. Inthe instance of the repeating closed cell surface structure, thefeatures to be measured are the largest of the cells in the closed-cellmatrix. For the surface structure comprising small pits separated bylarge plateaus, the large plateaus between pits are to be measured. Forthe surface comprising a field of small particles punctuated byintermittent large smooth regions, the intermittent large smooth regionsare to be measured. All surfaces with substantially varying morphologiescan thus be characterized using ALF.

In embodiments, the at least one roughened surface of the glass articlehas an average RMS roughness can be from about 10 nm to about 800 nm,from about 40 nm to about 500 nm, and from about 40 nm to about 300 nm.In embodiments, the average RMS roughness can be greater than about 10nm and less than about 10% of the ALF, greater than about 10 nm and lessthan about 5% of ALF, and greater than about 10 nm and less than about3% of ALF.

The specification of low DOI and high Ros/Rs provide constraints on thecharacteristic feature size and ALF. For a given roughness level, it hasbeen found that larger feature sizes result in lower DOI and higherRos/Rs. Therefore, to balance the display sparkle and the DOI target, inembodiments, it can be desirable to create anti-glare surfaces having anintermediate characteristic feature size that is neither too small nortoo large. It is also desirable to minimize reflected or transmittedhaze when the transmitted haze is scattering into very high angles thatcan cause a milky white appearance of a roughened article under ambientlighting.

“Transmission haze,” “haze,” or like terms refer to the percentage oftransmitted light scattered outside an angular cone of ±4.0° accordingto ASTM D1003. For an optically smooth surface, the transmission haze isgenerally close to zero. Transmission haze of a glass sheet roughened ontwo sides (Haze_(2-side)) can be related to the transmission haze of aglass sheet having an equivalent surface that is roughened on only oneside (Haze_(1-side)), according to the approximation of eq. (2):Haze_(2-side)≈[(1−Haze_(1-side))·Haze_(1-side)]+Haze_(1-side)  (2).Haze values are usually reported in terms of percent haze. The value ofHaze_(2-side) from eq. (2) must be multiplied by 100. In embodiments,the disclosed glass article can have a transmission haze of less thanabout 50% and even less than about 30%.

A multistep surface treatment process has been used to form theroughened glass surface. An example of a multistep etch process isdisclosed in commonly owned copending U.S. Provisional Patent Appln61/165,154, filed Mar. 31, 2009, to Carlson, et al., entitled “GlassHaving Anti-Glare Surface and Method of Making,” where a glass surfaceis treated with a first etchant to form crystals on the surface, thenetching a region of the surface adjacent to each of the crystals to adesired roughness, followed by removing the crystals from the glasssurface, and reducing the roughness of the surface of the glass articleto provide the surface with a desired haze and gloss.

In embodiments, various performance enhancing additives can be includedin the particle suspension, the etch solution, or both, including forexample, a surfactant, a co-solvent, a diluent, a lubricant, a gelationagent, and like additives, or combinations thereof.

The contacting the particulated surface with an etchant can involve, forexample, selective partial or complete dipping, spaying, immersion, andlike treatments, or a combination of treatments, with an acidic etchsolution including, for example, 2 to 10 wt % hydrofluoric acid and 2 to30 wt % of a mineral acid, such as hydrochloric acid, sulfuric acid,nitric acid, phosphoric acid, and like acids, or combinations thereof.The glass surface can be etched in the solution for periods of fromabout 1 second to about 10 minutes, including intermediate values andranges, with longer times generally leading to a greater reduction inthe surface roughness. The disclosed concentrations and etch times arerepresentative of suitable examples. Concentrations and etch timesoutside the disclosed ranges can also be used to obtain the roughenedsurface of the glass article albeit potentially less efficiently. Otheretch concentrations can be, for example, 3M HF/3.6 M H₂SO₄, 5.5M HF/6.5MH₂SO₄, 6M HF/7 M H₂SO₄, and like etch concentrations and compositions,including intermediate values and ranges.

In chemical strengthening, larger alkali metal ions are exchanged forsmaller mobile alkali ions near the glass surface. This ion-exchangeprocess places the surface of the glass in compression, allowing it tobe more resistant to any mechanical damage. In embodiments, the outersurface of the glass article can optionally be ion-exchanged wheresmaller metal ions are replaced or exchanged by larger metal ions havingthe same valence as the smaller ions. For example, sodium ions in theglass can be replaced with larger potassium ions by immersing the glassin a molten salt bath containing potassium ions. The replacement ofsmaller ions with larger ions creates a compressive stress within thelayer. In embodiments, the larger ions near the outer surface of theglass can be replaced by smaller ions, for example, by heating the glassto a temperature above the strain point of the glass. Upon cooling to atemperature below the strain point, a compressive stress is created inan outer layer of the glass. Chemical strengthening of the glass canoptionally be performed after the surface roughening treatment, withlittle negative effect on the ion-exchange behavior or the strength ofthe glass article.

In embodiments, the disclosure provides a method for making ananti-glare surface including, for example, “particulating” (i.e.,populating) the surface with particles, such as with a liquid suspensionor a soot gun, deforming or adhering the particulates to the surface,etching the adhered particulated surface with a suitable etchant,ion-exchanging the etched surface, and optionally accomplishing furtherprocessing to reduce objectionable surface flaws (i.e., flaw reduction).Alternatively or additionally, the surface can be ion-exchanged,particulated with particles, particles adhered to the surface, etchedwith an etchant, and optionally flaw reduction processed.

Referring to the figures, FIG. 1 schematically shows the steps in theprocess of creating an anti-glare layer on a GORILLA® glass surface. Waxparticles, or like deformable particles, having an average particle sizeof from about 0.1 to about 20 micrometers are suspended in a suitableliquid such as isopropyl alcohol, and the resulting suspension can bedeposited (100), for example, slot coated onto a glass substrate, andthe solvent removed to leave a residual layer of wax particles (105)weakly adhered on the glass substrate (110). The sample can then bedipped into or immersed in an acid etch (120) bath. The HF/H₂SO₄ etchantattacks the area around the wax particles and eventually under-cuts thearea covered by individual particles. The wax particles can be liberatedfrom the substrate surface during or after a rinse step (120) to createa textured surface (130) on the glass substrate having anti-glareproperties. FIG. 1 shows the general process of how the anti-glare layeris created on, for example, a Gorilla® Glass surface in using theslot-die process. The particles are first suspended in a liquid, such asisopropanol or like liquids, then the suspension is slot-die coated ontoa glass substrate. The solvent can be removed by any suitable means, forexample, evaporation, vacuum, hot air, and like means leaving a thinlayer of particles on the glass surface. Removing the solvent with hotair or like means can be sufficient and efficient enough to adhere thedeformable particles to the glass surface on a small, intermediate, orlarge scale. The sample can then, for example, be dipped into a HF/H₂SO₄etchant bath. The acid attacks the area around the particles andeventually under cuts the area of some or all of the particles. Some orsubstantially all of the particles come off the glass surface during therinsing to leave behind an etched surface to provide an anti-glare layeror anti-glare surface on the article.

FIG. 2 shows an example microscopic image of the wax particles that wereslot-die coated on a Gorilla® Glass surface. Numerous experimentsdemonstrated that the wax particles uniformly deposited on the glasssurface providing tiny openings, voids, or interstices between theparticles.

FIG. 3 shows an example microscopic image of the Gorilla® Glass surfaceof FIG. 2 that was subsequently thermally treated at 75° C. for 60seconds. The particles deformed and fused together and adhered well tothe glass surface. Substantially greater numbers of micro-openings canbe seen as the light shaded regions.

FIGS. 4A and 4B, respectively, show a microscopic image at two differentmagnifications of an example etched surface after the glass sample wasslot-die coated with a wax particle formulation and then thermallytreated (annealed) at 106° C. for 30 seconds. FIG. 4A shows a 200micrometer scale and FIG. 4B shows a 100 micrometer scale. The etchsolution used was 5.5M HF/6.5M H₂SO₄ and the sample was etched for 30seconds. The measured optical properties of the resulting surface were:haze=39 and DOI=44, sparkle=5.1

FIGS. 5A and 5B, respectively, show surface analysis images at high(FIG. 5A) and low (FIG. 5B) magnifications for surface roughness of anetched coupon after coating and thermal treatment at 106° C. for 30seconds and then 30 seconds etch time. The same area was captured withtwo different optical objectives (20× and 10×). The Ra=82 nm captured at20×, 2× zoom, and Ra=245 nm captured at 10×, 1× zoom. The etched surfacewas obtained with “6/7” acid solution (i.e., acid molarity ratio of 6 MHF/7M H₂SO₄) for 30 seconds.

FIGS. 6A and 6B show, respectively, exemplary microscopic images ofparticles that were slot-die coated on a Gorilla® Glass surface, beforeand after they were thermally treated at 75° C. for 30 seconds. Theimage location captured was at the same location in FIGS. 6A and 6B toshow the surface before (FIG. 6A top) and after (FIG. 6B bottom) 30seconds of wax particle surface with tiny openings after heat treatmentat 75° C.

FIGS. 7A and 7B show, respectively, exemplary microscopic images ofparticles that were slot-die coated on a Gorilla® Glass surface, beforeand after they were thermally treated at 85° C. for 30 seconds. Theimage location captured was at the same location in both FIGS. 7A and 7Bto show the surface appearance and condition before (7A, top) and after(7B, bottom) 30 seconds of particle surface deformation by heating at115° C.

FIG. 8A shows a histogram representing an example of the particle sizedistribution for an exemplary particle suspension formulation of Example1 measured by laser light scattering. FIG. 8B shows a histogramrepresenting another example of a particle size distribution for anexemplary monomodal particle suspension formulation consisting of DEUREXMM 8015 wax particles. The “% CHAN” refers to the relative numberpercentage of the particle size distribution within an average particlesize channel or bin, for example, 6.0+/−0.5 micrometers. The polymerparticle distribution profile has bimodal character substantiallybetween about 2 and 20 microns and centered around a particle size ofabout 8 to 10 microns. Other suitable particle sizes can be, forexample, 0.5 micrometers to about 20 microns, including intermediatevalues and ranges. Using particle sizes greater than about 20 micronscan result in the etched surface having increased sparkle.

The disclosed etch method can be accomplished quickly, for example, infrom about 1 second to about 10 minutes, from about 1 second to about 5minutes, including intermediate values and ranges, such as in from about2 second to about 4 minutes, to create an anti-glare layer on a glasssurface. A conventional multi-bath method can take about 60 minutes ormore. The disclosed etch method uses a single chemical etchant bath(e.g., HF and H₂SO₄) instead of three or more baths used in conventionalprocesses.

In embodiments, the disclosed method can etch away, for example, fromabout 1 to about 50 micrometers of the substrate being etched (i.e.,into the plane of the substrate or the z-direction), from about 1 toabout 30 micrometers of the substrate, from about 1 to about 20micrometers of the substrate, from about 1 to about 10 micrometers ofthe substrate, including intermediate values and ranges, to create adesired anti-glare layer. In contrast, a conventional etch process cantypically remove about 100 to about 200 micrometers of the glasssurface. Since relatively little glass is lost from the glass substrateusing the disclosed method, the glass can have a maximum warp of lessthan about 250 micrometers. A conventional glass etching process canproduce glass surfaces having, for example, about 300 micrometers ormore of warp.

Samples prepared with the disclosed process show similar opticalproperties (e.g., haze, gloss, and distinctness of image (DOI)) whencompared with samples etched with a conventional process, but thepresent method and samples are advantaged by having substantialreductions in process time and costs. The disclosed process is readilyscaled-up for large parts, such as a one square meter glass sheet, andabove, while a conventional dip process is less readily scalable forlarger units.

With a proper design selection, the disclosed process does not needbackside protection to make single-sided samples. Single-sided samplescan be prepared using for example, single-side dip, spray, screenprinting, or spin coating methods. A multi-bath conventional processneeds backside protection film, which can further increase manufacturingcosts.

In embodiments, the glass article can comprise, consist essentially of,or consist of one of a soda lime silicate glass, an alkaline earthaluminosilicate glass, an alkali aluminosilicate glass, an alkaliborosilicate glass, and combinations thereof. In embodiments, the glassarticle can be, for example, an alkali aluminosilicate glass having thecomposition: 60-72 mol % SiO₂; 9-16 mol % Al₂O₃; 5-12 mol % B₂O₃; 8-16mol % Na₂O; and 0-4 mol % K₂O, wherein the ratio

${\frac{{{Al}_{2}{O_{3}\left( {{mol}\mspace{14mu}\%} \right)}} + {B_{2}{O_{3}\left( {{mol}\mspace{14mu}\%} \right)}}}{\sum{{alkali}\mspace{14mu}{metal}\mspace{14mu}{modifiers}\mspace{14mu}\left( {{mol}\mspace{14mu}\%} \right)}} > 1},$where the alkali metal modifiers are alkali metal oxides. Inembodiments, the alkali aluminosilicate glass substrate can be, forexample: 61-75 mol % SiO₂; 7-15 mol % Al₂O₃; 0-12 mol % B₂O₃; 9-21 mol %Na₂O; 0-4 mol % K₂O; 0-7 mol % MgO; and 0-3 mol % CaO. In embodiments,the alkali aluminosilicate glass substrate can be, for example: 60-70mol % SiO₂; 6-14 mol % Al₂O₃; 0-15 mol % B₂O₃; 0-15 mol % Li₂O; 0-20 mol% Na₂O; 0-10 mol % K₂O; 0-8 mol % MgO; 0-10 mol % CaO; 0-5 mol % ZrO₂;0-1 mol % SnO₂; 0-1 mol % CeO₂; less than 50 ppm As₂O₃; and less than 50ppm Sb₂O₃; wherein 12 mol %≦Li₂O+Na₂O+K₂O≦20 mol % and 0 mol%≦MgO+CaO≦10 mol %. In embodiments, the alkali aluminosilicate glasssubstrate can be, for example: 64-68 mol % SiO₂; 12-16 mol % Na₂O; 8-12mol % Al₂O₃; 0-3 mol % B₂O₃; 2-5 mol % K₂O; 4-6 mol % MgO; and 0-5 mol %CaO, wherein: 66 mol %≦SiO₂+B₂O₃+CaO≦69 mol %;Na₂O+K₂O+B₂O₃+MgO+CaO+SrO>10 mol %; 5 mol %≦MgO+CaO+SrO≦8 mol %;(Na₂O+B₂O₃)—Al₂O₃≦2 mol %; 2 mol %≦Na₂O—Al₂O₃≦6 mol %; and 4 mol%≦(Na₂O+K₂O)—Al₂O₃≦10 mol %. In embodiments, the alkali aluminosilicateglass can be, for example: 50-80 wt % SiO₂; 2-20 wt % Al₂O₃; 0-15 wt %B₂O₃; 1-20 wt % Na₂O; 0-10 wt % Li₂O; 0-10 wt % K₂O; and 0-5 wt %(MgO+CaO+SrO+BaO); 0-3 wt % (SrO+BaO); and 0-5 wt % (ZrO₂+TiO₂), wherein0≦(Li₂O+K₂O)/Na₂O≦0.5.

In embodiments, the alkali aluminosilicate glass can be, for example,substantially free of lithium. In embodiments, the alkalialuminosilicate glass can be, for example, substantially free of atleast one of arsenic, antimony, barium, or combinations thereof. Inembodiments, the glass can optionally be batched with 0 to 2 mol % of atleast one fining agent, such as Na₂SO₄, NaCl, NaF, NaBr, K₂SO₄, KCl, KF,KBr, SnO₂, at like substances, or combinations thereof.

In embodiments, the selected glass can be, for example, down drawable,i.e., formable by methods such as slot draw or fusion draw processesthat are known in the art. In these instances, the glass can have aliquidus viscosity of at least 130 kpoise. Examples of alkalialuminosilicate glasses are described in commonly owned and assignedU.S. patent application Ser. No. 11/888,213, to Ellison, et al.,entitled “Down-Drawable, Chemically Strengthened Glass for Cover Plate,”filed Jul. 31, 2007, which claims priority from U.S. ProvisionalApplication 60/930,808, filed May 22, 2007; U.S. patent application Ser.No. 12/277,573, to Dejneka, et al., entitled “Glasses Having ImprovedToughness and Scratch Resistance,” filed Nov. 25, 2008, which claimspriority from U.S. Provisional Application 61/004,677, filed Nov. 29,2007; U.S. patent application Ser. No. 12/392,577, to Dejneka, et al.,entitled “Fining Agents for Silicate Glasses,” filed Feb. 25, 2009,which claims priority from U.S. Provisional Application No. 61/067,130,filed Feb. 26, 2008; U.S. patent application Ser. No. 12/393,241, toDejneka, et al., entitled “Ion-Exchanged, Fast Cooled Glasses,” filedFeb. 26, 2009, which claims priority to U.S. Provisional Application No.61/067,732, filed Feb. 29, 2008; U.S. patent application Ser. No.12/537,393, to Barefoot, et al., entitled “Strengthened Glass Articlesand Methods of Making,” filed Aug. 7, 2009, which claims priority toU.S. Provisional Application No. 61/087,324, entitled “ChemicallyTempered Cover Glass,” filed Aug. 8, 2008; U.S. Provisional PatentApplication No. 61/235,767, to Barefoot, et al., entitled “Crack andScratch Resistant Glass and Enclosures Made Therefrom,” filed Aug. 21,2009; and U.S. Provisional Patent Application No. 61/235,762, toDejneka, et al., entitled “Zircon Compatible Glasses for Down Draw,”filed Aug. 21, 2009.

The glass surfaces and sheets described in the following example(s) canbe any suitable particle-coatable and etchable glass substrate or likesubstrates, and can include, for example, a glass composition 1 through11, or a combination thereof, listed in Table 1.

TABLE 1 Representative glass substrate compositions. Oxides Glass (mol%) 1 2 3 4 5 6 7 8 9 10 11 SiO₂ 66.16 69.49 63.06 64.89 63.28 67.6466.58 64.49 66.53 67.19 70.62 Al₂O₃ 10.29 8.45 8.45 5.79 7.93 10.6311.03 8.72 8.68 3.29 0.86 TiO₂ 0 — — 0.64 0.66 0.056 0.004 — 0.089 Na₂O14 14.01 15.39 11.48 15.51 12.29 13.28 15.63 10.76 13.84 13.22 K₂O 2.451.16 3.44 4.09 3.46 2.66 2.5 3.32 0.007 1.21 0.013 B₂O₃ 0.6 1.93 — 1.9 —— 0.82 — 2.57 — SnO₂ 0.21 0.185 — — 0.127 — — 0.028 — — — BaO 0 — — — —— — 0.021 0.01 0.009 — As₂O₃ 0 — — — — 0.24 0.27 — 0.02 — Sb₂O₃ — — 0.07— 0.015 — 0.038 0.127 0.08 0.04 0.013 CaO 0.58 0.507 2.41 0.29 2.480.094 0.07 2.31 0.05 7.05 7.74 MgO 5.7 6.2 3.2 11.01 3.2 5.8 5.56 2.630.014 4.73 7.43 ZrO₂ 0.0105 0.01 2.05 2.4 2.09 — — 1.82 2.54 0.03 0.014Li₂O 0 — — — — — — — 11.32 — — Fe₂O₃ 0.0081 0.008 0.0083 0.008 0.00830.0099 0.0082 0.0062 0.0035 0.0042 0.0048 SrO — — — 0.029 — — — — — — —

EXAMPLES

The following examples serve to more fully describe the manner of usingthe above-described disclosure, and to further set forth the best modescontemplated for carrying out various aspects of the disclosure. It isunderstood that these examples do not limit the scope of thisdisclosure, but rather are presented for illustrative purposes. Theworking examples further describe the methods and how to make thearticles of the disclosure.

Example 1

Preparation of Particle Suspensions

This example is one exemplary procedure for accomplishing the presentmethod. The steps of how the glass was coated, thermally treated, thenetched are described below. A 2318 glass (6″×6″) specimen was washed inthe washer (Crest Line) using about 4% detergent the in deionized (DI)water. The washed glass sheets were then laid on a flat surface and33.33 wt % of DEUREX ME 1519 wax particles were weighed into a containerand 66.64 wt % of 2-propanol was added. DEUREX ME 1519 wax particles areavailable from DEUREX Micro-Technologies; Germany (www.deurex.com). Thecontainer was processed for five minutes on a Resodyn™ Acoustic Mixer atthe 60% power level. The resulting particle size distribution measuredby laser light scattering is shown in FIG. 8A. The concentratedsuspension could be used directly without further modification or couldbe stored, for example, for about 1 week if continuously rolled prior touse.

Example 2

Preparation of Particulated Surfaces—Coating or Depositing ParticleSuspensions

This example is an exemplary procedure for coating or depositing a waxparticle suspension on the glass surface. The particle suspension ofExample 1 was hand-coated onto a glass sheet using a 1 mil (25 microns)drawdown bar.

The volatile liquid or solvent was evaporated in air or with accelerateddrying methods, such as vacuum, mild heating, or combinations thereof.The residual surface layer of the wax particulates partially protectsunderlying or supporting portions of the glass substrate surface, sothat during acid etching not all of the substrate is etched away.Particulate suspension preparation can include, for example, a two stepprocess comprising, for example, preparing a concentrate stocksuspension, and then prior to surface application, the concentrate canbe reduced in concentration or let-down by adding (diluting) a volatileliquid that can readily evaporate after application. In embodiments, thedilute suspension is stable for a period of, for example, several daysto weeks, and can be re-suspended by rolling or shaking.

The following is an exemplary hand coating procedure.

A small amount (1 mL) of particle suspension was poured onto the glasssample. Use a 25 micrometer gap drawdown bar to sweep the pouredparticle suspension from one end to the other of the glass sample. Athin film with 25 micrometer wet thickness remains on the glass.

With the coated side up, the glass was placed on a hot plate set, forexample, at 75° C. for 40 seconds.

After the thermal treatment, the sample was then dipped into an etchantbath containing an acid solution having a specific concentration, forexample, a 5.5M HF/6.5M H₂SO₄ for a specific time, e.g., 30 seconds. Theresulting etched sample was then removed from the acid bath and rinsed.An optional organic solvent rinse can be used if there is any waxparticle mask residue. For example, acetone or like solvents, areparticularly useful for removing many different types of polymerparticles. The coupon was allowed to dry before measuring the haze,sparkle, and DOI, of the etched samples.

Different methods for applying the particles can be selected. Forexample, the particle suspension could be sprayed, curtain-coated,screen-printed, dip-coated, spin-coated, applied with a roller,rod-coated, roll-coated, and like methods, or combinations thereof. Manyof the examples in the disclosure were prepared using slot-die coatingmethod, which method has a number of production and productivityadvantages. An advantage of the slot-die coating technique is that thecoating thickness can be precisely controlled. After coating and thermaltreatment, a very thin layer (of about only 1 to 2 layers, or in someinstances less than a complete monolayer) of particles remained on thesurface. This type of coating improves the ability of the acid topermeate or infiltrate the spaces in the particle coating mask,resulting in, for example, more efficient etching, less acidconsumption, and less particle consumption. Further process improvementsinclude, for example, optimizing the interaction between the particlesand the glass surface by adjusting the glass or the particle properties,particle concentration, surface charge properties, or combinationsthereof. In embodiments, a preferred wet coating method applies onlyabout 1 to 2 particle layers, or even less than a monolayer to the glasssurface. Table 2 shows examples of various thermal set points whilekeeping the thermal treatment time the same. The same acid etchantconcentrations were used.

TABLE 2 Heat- Heat- Particle ing ing Acid Etch size Temp Time Concen-Time Spar- (microns) (° C.) (sec) tration (sec) DOI Haze kle 50% < 6;100 30 6M HF 30 65 7.4 5.9 99% < 19 102 7M H₂SO₄ 53 12.3 6.1 104 37 28.45 106 26 44 6.5 108 26 45.6 110 26 58.5 visual rat- ing <6

As the treatment temperature is increased, more particles fused togetherand have stronger adhesion on the glass surface and thus allowed theacid to etch more into the glass. This was clearly demonstrated in Table1 when the haze level increased and the DOI became lower. When heattreated at a low temperature, the particles didn't fuse together and hadpoor adhesion on the glass. The particles could be easily washed off thesurface or were undercut quickly by the acid. This resulted in a highDOI and low haze values.

Even with very short etch times in HF/H₂SO₄ solution, high to very highhaze target with good DOI were achieved. The sparkle was very low andthe anti-glare appearance properties were judged to be excellent bynumerous observers. This clearly demonstrated that using polyethylenewax particle formulations as a masking layer gave superior opticalperformance.

Table 3 shows more examples of using polyethylene wax particles tocreate anti-glare layer on Gorilla® Glass. Samples were heat treated atdifferent temperatures and etched for a shorter time. The results inTable 3 show that when a shorter etching time was used, the DOI went upwhile keeping the haze and sparkle similar. This demonstrates theflexibility and less glass thickness loss.

TABLE 3 Heat- Heat- Particle ing ing Acid Etch size Temp Time Concen-Time Spar- (microns) (° C.) (sec) tration (sec) DOI Haze kle 50% < 6;100 30 6M HF 20 65 10 5.8 99% < 19 102 7M H₂SO₄ 60 15 5.6 104 42 25 5.2106 26 45 5.9 108 26 46 5.9 110 26 58 visual rat- ing <6

Table 4 shows more examples of using the low molecular weightpolyethylene wax particles to create anti-glare layer on Gorilla® Glass.Samples were heated at different temperatures and etched at a lower acidconcentration. With lower acid concentration, high haze to very highhaze was still achieved with excellent sparkle. It is expected that evenlower acid concentrations can be used to achieve similar results by, forexample, adjusting particle heating temperature, heating time, particleconcentration, etching temperature, coating thickness, etch time, orcombinations thereof

TABLE 4 Heat- Heat- Particle ing ing Acid Etch size Temp Time Concen-Time Spar- (microns) (° C.) (sec) tration (sec) DOI Haze kle 50% < 6;100 30 5.5M HF 30 71 6.8 5.4 99% < 19 102 6.5M H₂SO₄ 70 7.4 5.2 104 5719 5.4 106 30 30 5.6 108 29 32 5.3 110 26 51 visual rat- ing <6

The particles used were based on low molecular polyethylene particle,having a relatively low Tg. A wide variety of alternative polymerparticles having an annealing temperature to be roughly proportional tothe Tg of the polymer particles can be selected. Examples of otherpolymer particle materials include, for example, polystyrene,polyesters, polyolefins, polyvinylchloride, polyvinyl acetate, polyvinylalcohol, polyacrylonitrile, silicone, polyethylene, melamine,(meth)acrylate, polyethylene terephthalate. The particles can behomopolymers, copolymers, or mixtures thereof. The beads can be modifiedwith a surface treatment such as cross-linking, a temperature orradiation sensitive shell, and like modifications, or combinationsthereof. The particles can be crosslinked or uncrosslinked, andspherical or flattened fine particles form factors comprised of aplastic can be used. Other suitable alternative materials include, forexample, waxes or polymers having wax-like properties and areparticularly effective in achieving the features and aspects of thedisclosure. Classes of waxes can be, for example, plant, mineral, oranimal-based, including petroleum derived and synthetic waxes. Someexample waxes include erucamide, stearamide, oleamide, Montan, oxidizedpolyethylene, copolymers containing these combinations, and particleshaving a core of one polymer and shell of a different polymer, and otherlike materials. The other polymer particle types can be selected basedon various considerations including cost, ease of removal, or robustnessin acid solutions.

The polymer particle size need not be limited. For anti-glare surfacesin display applications, a generally desirable particle size range canbe, for example, from about 1 micron to about 50 microns, includingintermediate values and ranges. Below this range, sub-wavelength effectscan reduce the anti-glare scattering, and above this range, unacceptabledisplay ‘sparkle’ can become visible in some pixelated displays.However, the disclosed process is still believed to be applicable usingparticle sizes outside this range. For example, the slot die coatingmethod can be used to create a several layers of particles, and controlthe final glass roughness through heating of a particle mask beforeetching. Particles larger than 50 microns can be useful in non-displayapplications, such as in mouse pads or other touch input devices,anti-glare surface for non-pixelated displays, and like applications.Polymer particles less than about 1 micron can be useful for generatingnano-structured surfaces, for example gradient-index anti-reflectioncoatings or hydrophobic or oleophobic structured surfaces. Othernon-display applications that can benefit from the disclosed method isto create light-scattering surfaces on glass including photovoltaicpanels for improved light trapping or light absorption, and aestheticpanels or covers for appliances or architectural applications.

Example 3

Preparation of Particulated Surfaces

DEUREX MM 8015 was slot-die coated according to the conditions listed inTable 5, where S-Gap (um) is the starting slot pour dimension inmicrometers, C-Gap (um) is the coating gap slot dimension inmicrometers, Horiz Del and Vert Del are time delays, and Liq Trig (mm)is the dimension when the slot-die pump shuts off at the end of thecoating run. Table 6 provides etch conditions and results.

TABLE 5 Slot Die Coating Conditions Aim S- C- Width Wet mm/ ml/ Gap GapHoriz Vert Liq (mm) (microns) sec min (um) (um) Del Del Trig 149.225 1350 5.82 90 90 0.1 0.1 4

TABLE 6 Etch data Particle size Distribution and Heat Temp HeatTreatment Acid Etch Time Properties (microns) (° C.) Time (seconds)Concentration (sec) DOI Haze Sparkle 50% < 5 um 69 30 5.5M HF 30 27 425.5 99% < 15 um 6.5M H₂SO₄

Example 4

Preparation of Mixed Particulated Surfaces

DEUREX MM 8015 material or like materials, if desired, can be mixed withother particulate materials or other performance additives, for example,a mixture of wax particles and polymer particles. Particle suspensionswere coated with same slot-die settings as above. A DUEREX particlesuspension was prepared as above. A polymer particle suspension, forexample, PMMA or like polymers or copolymers, such as a copolymer ofmethylmethacrylate and ethyleneglycoldimethacrylate, was preparedaccording to a formulation listed in Table 7. Alternatively, one or moreof, for example, a viscosity modifier, a binder, or a dispersing agentmay be omitted from the formulation.

TABLE 7 Representative polymer particle suspension formulations.Formulation component (wt %) 1 2 3 Medium 80 863 Solvent blend¹ 11.4811.48 11.48 Ethanol 70.86 70.86 70.86 Disperbyk² 0.31 0.31 0.31 BYK 420³2.04 2.04 2.04 Polymer particle @ 8 micrometers 15.28 Polymer particle @12 micrometers 15.28 Polymer particle @ 20 micrometers 15.28 Total 100100 100 ¹Medium 80 683 (a binder from Ferro; 8% cellulose derivative inmixed solvent; denatured ethanol, ca. 40 wt %, diethylene glycolmonomethylether, ca. 60 wt %). ²Disperbyk, from Byk Chemie, iscarboxylic acid copolymer wetting and dispersing additive. Disperbyk perse was used in these formulations. ³Byk 420, from Byk Chemie, isathixotropic rheology modifier consisting of a modified urea inN-methylpyrrolidone. ⁴Polymer particle is a copolymer ofmethylmethacrylate and ethyleneglycoldimethacrylate purchased fromSekisui Products LLC.

Other polymer particle sizes, particle compositions, mixing two or moreparticle sizes with same or different compositions together, or glasssubstrates may involve additional or further formulation manipulation toproduce finished substrates having the desired roughness, haze level,and DOI properties in the finished article.

A mixed suspension was prepared by combining 90 wt % of DEUREX waxsuspension with 10 wt % of the polymer particle suspension, and themixed suspension was placed on a roller for about an hour to provide auniform mixture. The mixture was then slot-die coated with same settingas above. Particle coated samples were then heated for 45 seconds at 75°C., and followed by chemical etching. Table 8 lists the etch conditionsused and the properties of the resulting anti-glare glass. This exampledemonstrates that the addition of cross-linked polymer particles to theDEUREX material can provide good optical properties in the resultinganti-glare Gorilla® Glass.

TABLE 8 Mixed Particle Mask Etch Data. Heat Particle Heat Treatment AcidEtch size Temp Time Concen- Time Spar- (microns) (° C.) (sec) tration(sec) DOI Haze kle 90% 75 45 5.5M HF 30 40 25 63 DEUREX 6.1M H₂SO₄ 8015and 75 5.5M HF 43 30 6.1 10% 6.5M H₂SO₄ PMMA¹ ¹PMMA is a cross-linkedpolymethylmethacrylate polymer particle having an average diameter ofabout 5 microns.

The disclosure has been described with reference to various specificembodiments and techniques. However, it should be understood that manyvariations and modifications are possible while remaining within thescope of the disclosure.

What is claimed is:
 1. A glass article having an anti-glare surface,prepared by the process comprising: depositing deformable particles on aportion of at least one glass surface of the article comprisingcontacting the glass surface with a suspension of wax particles, asuspension of polymer particles, or a combination thereof; deforming thedeposited deformable particles on the surface by heating to adhere theparticles to the glass surface; contacting the glass surface having theadhered particles with an etchant to form the anti-glare surface,wherein contacting comprises exposing the glass surface having theadhered particles to the etchant for about 1 second to about 30 minutes;and removing the adhered particles from the glass surface, wherein theglass surface comprises at least one of a soda lime silicate glass, analkaline earth aluminosilicate, glass, an alkali aluminosilicate, glass,an alkali borosilicate glass, a boroaluminosilicate glass, or acombination thereof, the etchant comprises at least one acid selectedfrom HF, H₂SO₄, or a combination thereof, the resulting glass article isa monolith or a single piece of glass; the resulting glass article has ahaze of less than 30, a distinctness-of-image (DOI 20°) of 25 to 85, asurface roughness (Ra) of 50 to 500 nm, and an average roughnesspeak-to-valley difference profile of about 0.1 to about 10 micrometers,and the anti-glare surface comprises a distribution of topographicfeatures having an average diameter of about 1 to about 100 micrometers.2. The glass article of claim 1 wherein the haze is from about 0.1 toless than about
 30. 3. The glass article of claim 2 wherein the articleis a sheet of protective cover glass of a display device.
 4. A displaysystem comprising: a glass panel having at least one roughenedanti-glare surface prepared by the method comprising: depositingdeformable particles on a portion of at least one glass surface of thearticle comprising contacting the glass surface with a suspension of waxparticles, a suspension of polymer particles, or a combination thereof;deforming the deposited deformable particles on the surface by heatingto adhere the particles to the glass surface; contacting the glasssurface having the adhered particles with an etchant to form theanti-glare surface, wherein contacting comprises exposing the glasssurface having the adhered particles to the etchant for about 1 secondto about 30 minutes; and removing the adhered particles from the glasssurface, wherein the glass surface comprises at least one of a soda limesilicate glass, an alkaline earth aluminosilicate glass, an alkalialuminosilicate glass, an alkali borosilicate glass, aboroaluminosilicate glass, or a combination thereof, the etchantcomprises at least one acid selected from HF, H₂SO₄, or a combinationthereof, the resulting glass article is a monolith or a single piece ofglass; the resulting glass article has a haze of less than 30, adistinctness-of-image (DOI 20°) of 25 to 85, a surface roughness (Ra) of50 to 500 nm, and an average roughness peak-to-valley difference profileof about 0.1 to about 10 micrometers having a pixelated image-displaypanel adjacent to the glass panel, and the anti-glare surface comprisesa distribution of topographic features having an average diameter ofabout 1 to about 100 micrometers.